Pneumatic controlling and cushioning device



Nov. 2, 1965 G. R. BUNNELL 3,215,

PNEUMATIC CONTROLLING AND CUSHIONING DEVICE Filed Aug. 29, 1962 United States Patent 3,215,229 PNEUMATIC CONTROLLING AND CUSHIONING DEVICE Glenn R. Bunnell, Dear-born, Mich., assignor to Special Engineering Service, Inc., Dearborn, Micl1., a corporation of Michigan Filed Aug. 29, 1962, Ser. No. 220,266 6 Claims. (Cl. 18897) This invention relates to cushioning devices and in particular to an air-operated cushioning device which may be used with apparatus such as stock feeding devices for effectively slowing down and stopping the same without bounce or oscillatory motion of the device which cyclically must come to sudden stops for precisely positioning the stock in a stamping or forming press and the like.

Such apparatus as metal strip stock feeding devices for automatic press operation are provided with such cyclically operating structure for gripping the stock, advancing it to a position within a press, releasing the stock and then returning to its initial position to again grip the stock and advance it.

The present application is a continuation-in-part of application Serial No. 120,297 filed by me on June 28, 1961.

Heretofore, the problem of cushioning the impact of the moving parts of such apparatus as stock feeding devices against their stops has not been satisfactorily solved, particularly when air is used for providing the power to move the stock feeding carriage and for providing the fluid cushion for the carriage. Applicants cushioning device utilizes pressurized air as the cushioning fluid in a unique combination of interconnected cushioning cylinders, and adjustable air orifice interconnecting the cylinders, and a check valve which allows the double acting piston or pistons to pump additional air into the cushioning device in order to get improved cushioning at the end of the feed stroke of the stock feeding device and greatly reduced bounce particularly at the start of the operation of said stock feeding device. It is noted that generally, the conventional air cushioning devices mentioned above utilize air at atmospheric pressure for the cushioning effect, and these devices therefore resemble simple dashpot-type structures. In applicants invention a pair of separate cylinders are provided, which cylinders are interconnected by a passage containing an adjustably restricted orifice so that the air compressed in one of the cylinders is forced into the other of the cylinders to thereby charge that cylinder and reduce the tendency of the pistons to bounce. The adjustable restriction in the passage interconnecting the cylinders allows the device to be adapted for various speeds of operation and for various weights of stock which speed and weight variations vary the momentum which the cushioning device must overcome in bringing the feed stroke to a stop without bounce or shock. Compressed air is constantly applied through a check valve to the system comprising the cylinder chambers and interconnecting passage.

A general object of this invention is to provide an airoperated cushioning device having improved resistance to shock and bounce.

A specific object is to provide an air cushioning device with air pumping structure to increase the capacity of the device to cushion shock.

Further objects and advantages of the present invention will become apparent from the following description and drawings in which:

FIGURE 1 represents a longitudinal cross sectional view of one form of applicants cushioning device utilizing two pistons, with parts of the work or stock carrier shown; and

FIGURE 2 is a longitudinal cross sectional view of another embodiment of the invention utilizing a single piston.

Referring to FIGURE 1 of the drawing, a work carrier 10, which may be provided with sheet metal or other stock grippers well-known to the art, is segmentally shown and supports and carries applicants cushioning device generally designated 12 and comprising a housing 14 providing a first cylinder 16 and a second cylinder 18. End caps 20 provided with a plurality of air dumping or ex haust ports 22 therein are threadably received at 24 on the ends of each of the cylinders. A pair of pistons 26 and 28 are located, respectively, in cylinders 16 and 18 are interconnected by shaft 30. Shaft 30 is provided with threaded stud portions 32 and 34 threadably received in shafts 36 and 38, respectively, which extend through oversized apertures 40 in each of the end caps 20. Shaft 30 is slida-bly mounted in a dividing wall 42 separating the cylinders 16 and 18. Pistons 26 and 28 are shown as provided with expandable piston rings 44 and corrugated spring-type ring expanders 45 for providing a substantially air-tight seal between each of the pistons and its cylinder. It is noted that various rubber-type seals could be substituted for the piston rings 44 and expanders 45, for example, O-ring seals would be useful.

A passage or bleed orifice 46 provided in wall 42 allows transfer of air between cylinders 16 and 18, and the size of passage 46 is controlled by means of a needle type flow control valve 48. It is seen that as needle valve 48 is screwed down into the embossment 50 in which it is threadably mounted, the orifice 46 will become restricted and reduce the flow rate therethrough. It is noted that as the mass of the stock load increases, this valve 48 may be threaded further into the passage 46 to provide increased air resistance to the momentum of the stock and carriage.

Cylinder 16 communicates with a source of air pressure 52 through a lubricating mechanism 54, a flow control valve 56 and a check valve generally designated 58. Valve 58 is provided with an inlet port 60 which is closed by a ball 62 as the pressure in cylinder 16 exceeds the pressure in the feed line 64. It is noted that as the ball 62 is urged against the plate 66, air can circumvent the ball 62 and pass through the ports 68 in plate 66 into cylinder 16.

The carrier 10 may be of the general type shown in applicants prior Patent No. 2,978,160, issued April 4, 1961, and may include a work holding clamp which is adapted to clamp a workpiece such as a sheet of steel and advance the same in response to the movement of the carrier 10. This carrier may conveniently be operated by means of the fluid actuated piston 70, the shaft 72 of which may be operatively connected to the carrier. Piston may be mounted in a 2-way air cylinder 74 connected to a double acting valve 76 connected to the pressure source 52 through conduit 78. Valve 76 may be operated by any conventional means such as a limit switch actuatable by the ram of a press so that as the ram of the press retracts, the valve 76 will allow fluid to enter chamber 80 of the cylinder 74 to urge the work carrier and cushioning device 12 to the right in FIGURE 1 to position another portion of the workpiece properly on the press for subsequent working by the .press. After the workpiece is so positioned, any movement thereafter of the press ram may then cause valve 76 to reverse the operation of the piston 70 after the work grippers associated with carrier 10 have released the workpiece, to move the carrier 10 and cushioning device 12 to the left as shown in FIGURE 1, at which position the carrier is then in a position to grip the workpiece again for advancing another section thereof to the proper position on thepress. Cushioning device 12 is brought into cushioning operation by means of stops 81 and 82 normally axially spaced from the ends of shaft portions 36 and 38, respectively, but engageable thereby at the ends of the carriage stroke. These stops are stationarily positioned on the carrier bed or support 86 to limit the motion of the carrier and the workpiece carried therefor as well as operating the cushioning device. Each of these stops is shown as provided with a threaded shank 84 threadably received in the carrier bed 06 and having a nut 88 thereon for providing an adjustment and lock for the stop relative to the end caps 20 of the cushioning device.

In the operation of the cushioning device, air of preferably higher than atmospheric pressure is supplied to cylinder 16 to move the piston 26 and shaft 36 to the right as shown in the figure to position the shaft 36 and piston 26 in their cushioning positions. When it is desired to feed the stock, cushioning device 12 and work carrier 10 are moved to the right in the figure by means of air pressure in chamber 80 of the air cylinder '74. Near the end of the carrier stroke, shaft 36 will engage stop 81 at a predetermined distance from the working position on the press or other device and piston 26 will be forced to the left to compress air in cylinder 16. Simultaneously therewith, piston 28 will be forced to the left in the figure and air will be forced from cylinder 16 through orifice 46 into cylinder 18. The pressure in cylinder 16 will be great enough to force check ball 62 against its port 60 to prevent flow of fluid back through line 64. As the cushioning device 12 is moved to its extreme right position in the figure, and the workpiece is properly positioned on the press, the stop 81 will engage the end of cap and further motion of the cushioning device and the carrier 10 to the right will be prohibited. At this point there will exist in cylinder 18 air under pressure and any tendency of the cushioning device housing 14 and the carrier 10 connected thereto to bounce back to the left will be resisted by the relatively high air pressure in cylinder 18. If the piston 26 is moved in cylinder 16 a slight distance away from wall 42 by bouncing of the carrier and cushioning device, air is drawn past check valve 58 into the cylinder 16 by a momentary reduction in pressure in cylinder 16, and it is seen that a pumping action occurs due to the oscillation of the pistons with the result that additional air is drawn into the cylinders to increase the cushioning effect of the device 12 and prevent any significant harmonic frequency from developing in the cushioning device which would tend to enhance bounce. It is noted that the vents 22 in the caps 20 are sufficiently large so that compression of atmospheric air between the pistons 26 and 28 and caps 20 is an insignificant factor. It is further noted that applicants orifice 46 can be relatively large as compared to the orifices of cushioning devices which might employ air at atmospheric pressure. Consequently the size of orifice 46 can more readily and sensitively be adjusted by screw 48 to provide the exact cushioning effect of the device relatively to the speed and weight of the carrier 10 and its associated workpiece.

FIGURE 2 illustrates another embodiment of the invention, an improvement over the embodiment of FIG- URE 1, utilizing a single piston which acts within and separates the two interconnected chambers. The cushioning device is generally indicated at 101 and comprises a housing 102 providing a first chamber 103 and a second chamber 104 separated by a piston 105. The piston has shafts 106 and 107 extending from the opposite sides thereof through end caps 108 and 109, respectively, threaded on the ends of housing 102. Shafts 106 and 107 are adapted to engage fixed stops 111 and 112, respectively, for the above-described cushioning effect. A pair of seal retaining members 113 and 114 are mounted within the ends of chambers 103 and 104, respectively, and are held in place by end caps 108 and 109. Re taining members 113 and 114 carry seals 115 engageable with chambers 103 and 104, respectively, and seals 116 engageable with rods 106 and 107, respectively.

The reference numeral 117 indicates a portion of a work carrier analogous to the work carrier 10 of the previous embodiment, this carrier being reciprocable in the manner described above. Housing 102 is shown as extending through a bore 118 in work carrier 117, end caps 108 and 109 engaging work carrier 117 at the opposite ends of this bore and securing housing 102 thereto.

A passage 119 connects chambers 103 and 104, this passage extending between the outer ends of the chambers and being shown as formed between housing 102 and work carrier 117. Passage 119 comprises adjustable orifice means, a needle type flow control valve 121 being mounted in the adjacent portion of work carrier 117 and being disposed within passageway 119 to control the flow rate thereof. Needle valve 121 may be adjusted as described with respect to the previous embodiment.

Means are provided for applying compressed air to the system comprising chambers 103 and 104 and passage 119. This means includes a check valve generally designated at 122 having a connection 123 from a source of compressed air (not shown) which is closable by a ball 124 when the pressure in passage 119 exceeds that in connection 123. When ball 124 is urged against a perforated plate 125, the air can fiow around the ball and pass through the plate perforations and a connection 126 into the system comprising chambers 103 and 104 and passage 119.

In operation, assuming an initial condition as shown in FIGURE 2, rightward movement of work carrier 117 and housing 102 will result in shaft 106 engaging stop 111. With air of preferably higher than atmospheric pressure being supplied to connection 123, piston will be forced to the left by the engagement of shaft 106 with stop 111, compressing the air within chamber 104, the air traveling through passage 109 past restriction 121 to chamber 103. The pressure created will cause ball 124 to engage its seat, preventing back flow through connection 123, and the cushioning action will thus be as previously described. Rightward movement of work carrier 117 will continue until stop 111 engages end cap 108. Any momentary pressure reduction in the system will cause compressed air to be drawn past check valve 122 to increase the cushioning effect.

During leftward movement of work carrier 117, the action will be reversed, shaft 107 engaging stop 112 to cause rightward movement of piston 105 with respect to chambers 103 and 104. Air under pressure in chamber 103 will flow through passageway 119 past restriction 121 to chamber 104, creating a cushioning effect.

While it will be apparent that the embodiments of the invention herein disclosed are well calculated to fulfill the objects of the invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. An air operated cushioning device comprising separate cylinder means, piston means reciprocably mounted in each of said cylinder means, ends on said cylinder means, the spaces between said ends and piston being freely vented and unrestricted, whereby said piston means will remain adjacent its corresponding cylinder means end when forced thereto, shafts extending from said piston means through said ends, said piston means being connected for simultaneous movement, a compressed air source, conduit means for transmitting air from said source to one of said cylinder means, adjustable orifice means providing an air connection between said separate cylinder means, and check valve means in said conduit means for allowing air to flow into but not out of said. one cylinder means through said conduit means.

2. An adjustable air operated cushioning device for imparting controlled cushioning effect to stock feeding mechanisms and the like and reducing the tendency of the same to bounce at the end of the stroke of such mechanisms,

comprising a plurality of axially aligned cylinder means separated from each other by dividing wall means, piston means reciprocably mounted in each of said cylinder means, ends on said cylinder means, the spaces between said ends and pistons being freely vented and unrestricted, whereby said piston means will remain adjacent its corresponding cylinder means end when forced thereto, shafts extending from said piston means through said ends, said piston means being connected by shaft means for simultaneous movement, said shaft means being slidably mounted in aperture means in said dividing wall means, a source of pressurized air, conduit means for transmitting air from said source to one of said cylinder means, adjustable orifice means in said wall means providing a fluid bleed connection between said separate cylinder means, and check valve means in said conduit means for preventing flow of said air out of said one cylinder means through said conduit means as the piston means in said one cylinder means is being moved through its cushioning phase.

3. An air operated cushioning device comprising separate cylinder means, piston means in each of said cylinder means and connected for simultaneous movement, ends on said cylinder means, the spaces between said ends and pistons being freely vented and unrestricted, whereby said piston means will remain adjacent its corresponding cylinder means end when forced thereto, shafts extending from said piston means through said ends, a source of pressurized air, conduit means for transmitting air from said source to one of said cylinder means, orifice means providing a fluid bleed connection between said separate cylinder means, and check valve means in said conduit means for allowing air to flow into but not out of said cylinder means to allow sudden reductions in pressure within said cylinders due to movement of said piston means therein to pump additional air into said cylinder means.

4. An air operated cushioning device comprising separate axially aligned cylinder means separated by dividing wall means, piston means in each of said cylinder means and connected together for simultaneous movement by shaft means slidably mounted in aperture means in said wall means, ends on said cylinder means, the spaces between said ends and pistons being freely vented and unrestricted, whereby said piston means will remain adjacent its corresponding cylinder means end When forced thereto, shafts extending from said piston means through said ends, a source of pressurized air, conduit means for transmitting air from said source to one of said cylinder means, adjustable orifice means in said wall means providing a fluid bleed connection between said separate cylinder means, and check valve means in said conduit means for preventing flow of said air out of said one cylinder means through said conduit means as the piston means therein is being moved through its cushioning phase and for allowing movement of said piston means to pump additional air into said cylinder means.

5. An air operated cushioning device comprising separate axially aligned cylinder means separated by dividing wall means, piston means in each of said cylinder means and connected together for simultaneous movement by shaft means slidably mounted in aperture means in said wall means, ends on said cylinder means, the spaces between said ends and pistons being freely vented and unrestricted, whereby said piston means will remain adjacent its corresponding cylinder means end when forced thereto, shafts extending from said piston means through said ends, said piston means being spaced on said shaft means so that as one piston is positioned at the end of its cushioning stroke another piston means is positioned at the beginning of its cushioning stroke, a source of pressurized air, conduit means for transmitting air from said source to one of said cylinder means, adjustable orifice means in said wall means providing a fluid bleed connection between said separate cylinder means, and check valve means in said conduit means for preventing flow of said air out of said one cylinder means through said conduit means as the piston means therein is being moved through its cushioning phase and for allowing movement of said piston means to pump additional air into said cylinder means.

6. In an air operated cushioning device, a housing having a bore, a piston slidable within said housing and dividing the housing into first and second chambers, movement of said piston within said housing simultaneously causing one of said chambers to increase its volume and the other chamber to decrease its volume, a bypass extending through the wall of said housing and connected to the outer ends of said chambers, adjustable orifice means provided in said bypass, a compressed air source, conduit means for transmitting air from said source to said bypass, check valve means in said conduit means for allowing air flow into but not out of said bypass through said conduit means, a pair of shafts extending from opposite sides of said piston, means closing each of the outer ends of 'said first and second chambers, each one of said pairs of shafts extending through each of said last-mentioned means respectively, relative axial movement between said shafts and piston on one hand and said housing on the other hand being solely controlled by said bypass and orifice means, and a pair of stationarily positioned stops axially spaced from the ends of said shafts, the distance between said stops being greater than the distance between the ends of said shafts.

References Cited by the Examiner UNITED STATES PATENTS 444,183 1/91 Robinson 188-97.1 X

864,141 8/07 Scott 188-8851 1,099,073 6/14 Moir 267-8 1,205,818 11/16 Thomas 188-97.1 1,273,059 7/18 Hild 188-98 1,384,970 7/21 Rudy 188-88507 1,467,945 9/23 Moore et al. 188-8852 1,492,731 5/24 Kerr 188-88.1 1,590,414 6/26 Bosserdet 188-97.1 1,643,262 9/27 Steiner 188-97.1 2,978,160 4/61 Bunnell 226-151 ARTHUR L. LA POINT, Primary Examiner.

EUGENE G. BOTZ, Examiner. 

6. IN AN AIR OPERATED CUSHIONING DEVICE, A HOUSING HAVING A BORE, A PISTON SLIDABLE WITHIN SAID HOUSING AND DIVIDING THE HOUSING INTO FIRST AND SECOND CHAMBERS, MOVEMENT OF SID PISTON WITHIN SAID HOUSING SIMULTANEOUSLY CASUING ONE OF SAID CHAMBERS TO INCREASE ITS VOLUME AND THE OTHER CHAMBER TO DECREASE ITS VOLUME, A BYPASS EXTENDING THROUGH THE WALL OF SID HOUSING AND CONNECTED TO THE OUTER ENDS OF SAID CHAMBERS, ADJUSTABLE ORIFICE MEANS PROVIDED IN SAID BYPASS, A COMPRESSED AIR SOURCE, CONDUIT MEANS FOR TRANSMITTING AIR FROM SAID SOURCE TO SAID BYPASS, CHECK VALVE MEANS IN SAID CONDUIT MEANS FOR ALLOWING AIR FLOW INTO BUT NOT OUT OF SAID BYPASS THROUGH SAID CONDUIT MEANS, A PAIR OF SHAFTS EXTENDING FROM OPPOSITE SIDES OF SAID PISTON, MEANS CLOSING EACH OF THE OUTER ENDS OF SAID FIRST AND SECOND CHAMBERS, EACH ONE OF SID PAIRS OF SHAFTS EXTENDING THROUGH EACH OF SAID LAST-MENTIONED MEANS RESPECTIVELY, RELATIVE AXIAL MOVEMENT BETWEEN SAID SHAFTS AND PISTON ON ONE HAND AND SAID HOUSING ON THE OTHER HAND BEING SOLELY CONTROLLED BY SAID BYPASS AND ORIFICE MEANS, AND A PAIR OF STATIONARILY POSITIONED STOPS AXIALLY SPACED FROM THE ENDS OF SAID SHAFTS, THE DISTANCE BETWEEN SAID STOPS BEING GREATER THAN THE DISTANCE BETWEEN THE ENDS OF SAID SHAFTS. 